The so-called flying paster or speed matching system is well known in the trade where a new paper roll to be spliced is rotated so that the peripheral speed of the new paper roll agrees with the traveling speed of a traveling web to splice the start end of the new paper roll to the traveling web. Most important in an automatic splicing system is causing the peripheral speed of a new paper roll to agree with the traveling speed of a traveling web. Various techniques to achieve this were disclosed in Japanese Published Examined Patent Application No. Sho-49 (1974)-28601 and Japanese Published Examined Patent Application No. Hei-2 (1990)-33618.
Japanese Published Examined Patent Application No. Sho-49 (1974)-28601 discloses two means for detecting the peripheral speed of a new paper roll in an automatic paper-web splicing system in which the peripheral speed of a new paper roll is caused to agree with the traveling speed of a traveling web.
The first means comprises a rotating body coming in contact with the new paper roll to rotate in accordance with the rotation of the new paper roll, and pulse signal generating means for generating a pulse signal proportional to the rotation of the rotating body, thereby obtaining a voltage value proportional to the peripheral speed of the new paper roll.
The second means is as follows. A value proportional to the diameter value of the new paper roll and a value proportional to the rotating speed of the new paper roll are obtained, and a value proportional to the peripheral speed of the new paper roll is obtained by calculating both the signals. To obtain a value proportional to the aforementioned diameter value, the new paper roll R is supported by an open end of an arm 4 provided in an angularly movable manner, as shown in FIG. 6. The arm 4 is angularly moved to a position at which the outer peripheral edge of the new paper roll R is detected by the sensor K. The sensor K is provided at a predetermined location in the angularly movable range of the arm 4 in such a manner as to face the end face of the new paper roll R. Based on the fact that the amount of angular movement changes in accordance with the outside diameter of the new paper roll R, a voltage signal proportional to the amount of angular movement is amplified three times via a potentiometer 3 that interlocks with the angular movement of the arm 4, and then extracted as a signal proportional to the diameter value of the new paper roll R.
Japanese Published Examined Patent Application No. Hei-2 (1990)-33618 discloses the following technology. The rotating speed, that is, the number of rotations per a predetermined time of a new paper roll when the peripheral speed of the new paper roll agrees with the traveling speed of a traveling web is obtained by dividing the traveling speed of the traveling web by the peripheral surface length of the new paper roll. The rotation of the new paper roll is controlled to cause the new paper roll to be rotated at the rotating speed obtained so that the peripheral speed of the new paper roll agrees with the traveling speed of the traveling web.
A signal relating to the diameter, that is, the peripheral surface length (the peripheral surface length is the product of the diameter and a circular constant) of a new paper roll is obtained in the following manner. As shown in FIG. 7, a new paper roll R is supported by the open end of an arm provided in an angularly moveable manner, an appropriate arm phase (point a) is set as a reference phase, and a proximity switch and a sensor K are provided. When the arm reaches the reference phase, the proximity switch detects it and generates a reference signal. When the new paper roll R reaches an arm phase (point b) at which the new paper roll is pasted to the traveling web, the sensor K detects the outer peripheral edge of the new paper roll (the phase of the outer peripheral edge at that time is referred to as point c) and generates a detection signal. In the arrangement shown in FIG. 7, when the arm is angularly moved at a constant speed, the time required for the arm to move by a displacement angle (.theta.-.theta..sub.x) from the reference signal output (point a) to the detection signal output (point b) changes in accordance with changes in the outside diameter of the new paper roll R. Taking advantage of this fact, a signal relating to the diameter, that is, the peripheral surface length of the new paper roll R can be obtain by causing the arm to angularly move at a constant speed.
The aforementioned prior-art techniques, however, have the following problems.
In the first means disclosed in Japanese Published Examined Patent Application No. Sho-49 (1974)-28601, the rotating body rotating while making contact with the outer peripheral surface of the new paper roll tends to slip on the outer peripheral surface of the new paper roll. If the new paper roll is loaded off-center, the rotating body may be bounced on the outer peripheral surface of the new paper roll. As a result, it is difficult to obtain a voltage signal corresponding to the correct peripheral speed of the new paper roll. This results in a difference between the peripheral speed of the new paper roll and the traveling speed of the traveling web, causing many inconveniences, such as paper web breakage during splicing. Furthermore, the first means is prone to mechanical troubles, requiring frequent maintenance.
The second means disclosed in Japanese Published Examined Patent Application No. Sho-49 (1974)-28601 obtains a voltage signal relating to the diameter of the new paper roll using a potentiometer. This arrangement tends to cause a difference in the amount of mechanical movement due to fitting allowances given to ensure smooth movement. This difference adversely affects the accuracy, resulting in a relatively large error. The second means detects the diameter of the new paper roll by detecting the outer peripheral edge of the new paper roll and amplifying it three times with a potentiometer. When the new paper roll is loaded off-center, therefore, an error from the correct diameter, if any, may be exaggerated three times. Furthermore, when these two problems are combined, a great difference might be produced between the detected value and the actual value of the diameter of the new paper roll. As a result, the peripheral speed of the new paper roll cannot be made equal to the traveling speed of the traveling web, causing the trouble of web breakage during splicing.
The prior art disclosed in Japanese Published Examined Patent Application No. Hei-2 (1990)-33618 was proposed to address the problem stated in Japanese Published examined Patent Application No. Sho-49 (1974)-28601, the problem of a kind that could be solved easily only if the traveling speed of the traveling web is about 10 meters per second. However, with the recent progress in paper web printing where the traveling speed of the traveling web is required to be as high as 15 to 20 meters per second, even the technical solution disclosed in Japanese Published Examined Patent Application No. Hei-2 (1990)-33618 can cause inconveniences.
That is, in the technical solution disclosed in Japanese Published Examined Patent Application No. Hei-2 (1990)-33618, an electrical signal relating to the diameter of a new paper roll is obtained to use in the control of the rotation of the new paper roll. To obtain the electrical signal, the outer peripheral edge of the new paper roll is detected. If the new paper roll is loaded off-center, therefore, no correct electrical signal can be obtained. For this reason, controlling the rotation of the new paper roll based on the electrical signal inevitably causes some difference between the peripheral speed of the new paper roll and the traveling speed of the traveling web. In addition, the traveling speed of the traveling web in the recent technology has been increased 1.5 times to twice that of the traveling web in the conventional technology. This has made the aforementioned difference in speed even larger in proportion to the increase in the traveling speed of the traveling web. If the peripheral speed or the rotating speed of the new paper roll is increased with increases in the traveling speed of the traveling web, the centrifugal force exerted on the new paper roll increased accordingly. Thus, the wobbling of the rotating new paper roll becomes larger than the actual degree of off-center of the new paper roll. When these two factors are combined, a great difference is produced between the peripheral speed of the new paper roll and the traveling speed of the traveling web, resulting in paper breakage during splicing.